Positive pilot valve



July 14, 1942.

H. BARNETT POSITIVE PILOTVALVE Filed April 10, 1941 IN VEN TOR. Barrzc /ZZ'T nism and particularly to a Patented July 14, 1942 UNITED STATES PAT ENT OFFICE POSITIVE PILOT VALVE Harry Barnett, Chicago, 111., asslgnor to The Powers Regulator Company, Chicago, 111., a corporation of Illinois Application April 10, 1941, Serial No. 387,737

5Claims.

My invention relates to heat control mechapositive action pilot or relay valve.

An object of my invention is to provide valve mechanism of the type described in which extremely accurate control may be assured. This is essential for many types 01 industrial procsired temperature is required throughout the year in locations where heating or cooling are required, due to outdoor temperatures. It is customary to provide pilot valves for the purpose of cutting in or out the heating or cooling mediums, but it has not been possible in apparatus heretofore known to maintain accurate control at the critical point where a change is required from heating to cooling and vice-versa. Due to lack of sensitivity of control, it has not been esses and operations, particularly where a de-' possible to control the action within approxi-" mately 2 and occasions arise where, due to such lack of sensitivity, both heating and cooling have been supplied simultaneously.

In the apparatus here disclosed I am able to positively shift from heating to cooling control on a variation of approximately 1 6 01a degree no drag or overlapping Fahrenheit, there being of the two controls;

The invention will be more readily understood by reference to the accompanying drawing, in which, i

Fig. l'is a sectional view through a positive pilot valve constructed in accordance with my invention, it being noted, however, that the con,- necting pipes for the .variouselements of a system are shown diagrammatically for ease in understanding the air circuits;

Fig-2 is a diagrammatic lay-out of a typical installation, this, installation involving the use of a second, more simple, pilot valve and,

Fig. 3 is a sectional view through the last named pilot valve.

As ameans for facilitating the description 01" the valve which constitutesthe subject matter of my invention, 1 have indicated diagrammatically in Fig. 2 a system involving its use, this system comprising a direct-acting thermostat Ill controlled by an outdoor bulb II and supplied with air under pressure through the pipe l2. The re-' turn line l3 from this thermostat communicates with the entrance port C or the instrument of my invention, indicated generally by the numeral l4. Through'an outlet port D, and a pipe IS, the instrument is connected to a direct-acting,

air-controlled valve it which governs a supply of a heating medium through a pipe II. The pipe has a branch 22 communicating with the port A' of the secondary pilot valve shown in Fig. 3. A.

pipe 23 communicates with last-named valve and with a reverse acting air valve 24 controlling the delivery of a cooling medium froma plpe 25 to the pipe IS. The pipe 26 provides a connection between the port F of the instrument shown in Fig. land the port C of the instrument shown in Fig. 3. The port B and the stub pipe 21 01' instrument of the secondary pilot valve are open to the atmosphere.

The understanding as to the terms directacting and reverse-acting is as follows:

When thermostats, such as indicated at in and it, are influenced by an increase of temperature, an increased pressure is built up in their return lines and when a valve, such as shown at it in Fig. 2, is subjected to an increase pressure, the valve is closed. These are called direct-acting instruments. When, however, the reverse is true as in the valve shown in Fig. 2, the valve is opened by an increase in pressure and this is termed a reverse acting valve.

In the construction of Fig. l which, as before stated, is diagrammatical, so far as the pipe con- 9, port D of said nections are concerned, I provide' a casing consisting of two sections 3ll-.-3I joined by means of suitable flanges and serving to confine two diaphragms 32-43 which are spaced apart, and the space between which is open to the atmos phere as indicated at 34. The portion 30 of the casing provides two valve seats 35-36 controlled by valves 31-38. Springs are so placed as to tend to open the valve 31 and close the valve 38.

The space 46 between the outside wall of the the compression of the casing 30 and the diaphragm 33 is open to the outlet D which, as stated before, is in communication with the heat control valve Hi.

The valve 3'! controls the passage through the port B which is connected to the return pipe 20 of the room thermostat, while the valve 38 connects the port A and its connecting pipe H to a source of air under pressure.

In the portion in of the casing I' provide 9. diaphragm 45, one side of which is open to air delivered through the pipe l3 and the passage C. Aface plate 46 supports the diaphragm, the face plate being pressed by a coil spring 41, held by an adjusting nut 48, by means of which the action of the diaphragm 45 may be regulated.

Air under pressure is admitted through the pipe 2| to the port E, a restriction screw 49 being indicated in the passage. This pipe is open to the space behind the diaphragm 32 and in this space I provide a leak port 50, the outlet from which is controlled by a snap spring element 5|, the details of the construction of which are not important, since no claim is made herein as to such details. Such snap springs are known as Micro" springs and have the characteristics of a complete throw from one to another position by a movement of approximately .001 inch. This spring is contacted by a plunger 5la which engages the face plate 46. Thus upon the slightest movement of the diaphragm 46, the spring 5| is caused to close or open the leak port 50.

The operation of the valve thus far described is as follows:

Assuming the outdoor thermostat to be set at a temperature of 65, at any temperature under 65 no substantial pressure is admitted from the adapted to'be actuated by the diaphragm 51, the one being'open as the other is closed. The valve 59 opens the port B to the atmosphere while the valve 60 opens the port A to the branch pipe 22 connected to the room thermostat.

Thus it will be seen that as pressure builds up behind the diaphragm 32 of the instrument of Fig. 1, it is likewise built up in the passage F, the pipe 25 and the passage C in Fig. 3 behind the diaphragm 51. Movement of the said diaphragm willthus serve to close the valve 59, thus shutting off the escape of air to the atmosphere and opening the valve 60 which serves to place in communication the room thermostat with the port D and the pipe 23 to the reverse-acting cooling valve 24. Thus the room thermostat will then be in control of the cooling supply and upon an increase in room temperature, pressure will be admitted to the cooling valve 24, thus causing it to open and to admit a cooling medium to the space which is. to be controlled.

As the result of the described arrangement the shift from heating to cooling is positive and the actions cannot by any possibility overlap. Furline I! and thus no pressure will be delivered by the pipe I3 to the port C. Thus the diaphragm will remain in the position shown in the drawing, due to the action of the spring 41. In this position the snap spring will be away from the leak port and any air entering through the port E will be wasted through the leak port, thus allowing the diaphragm 32 to remainin the position shown in the drawing. In that position the valve 38 will remain closed, due to the action of its spring, and the valve 31 will remain open, due to the action of its spring. Thus the port B will be open to the-return line 20 fromth'e room ther mostat and through the port D and the pipe l5 to the heat control valve 16. Thus the room temperature will be controlled by the thermostat I5.

Assuming, however, that the temperature rises to a point very slightly above the 65 setting of the thermostat 10, air under substantial pressure will be admitted to the pipe |3,.the port.

C and the diaphragm 45. Following the slightest movement of said diaphragm, the snap spring 5| will be actuated to close the leak port 50 whereupon pressure admitted through the port E will build up behind the diaphragm 52, thus moving it inwardly and causing the unseating of the valve 38 and the seating of the valve 31. This serves to place in communication the port A andthe port D, thus admitting air under pressureto the line l5 and positively closing the direct-acting heat-control valve l6.v

A branch port F is open to the port E at a point past the restriction valve 49, and this port, through the pipe 26, communicates with the port C" of the instrument shown in Fig. 3. In the construction of Fig. 3 the instrument includes a two part casing -56 between which two diaphragms 5'|58 are held. The portion 55 of the pletely close said. leak port casing provides reversely positioned valves 59-55 15 thermore, such shift takes place following a very slight change of temperature, for example of a degree above or below the setting of the outdoor thermostat. In that connection it should be noted that neither the heating nor cooling valves can be openat the same time.

It will be noted also thatby providing the outlet F in the pilot valve, one or more auxiliary control valves, one of which is shown in Fig. 3, may be operated with pressure means that are exact in character with the pressure effective on the pilot valve. This has been. found to be an important consideration.

Only one of many adaptations of the pilot valve has been shown and described. Many means is not effective to move said valves, a second pressure-actuated means adapted to be operatively connected to a thermostat, and snap means co-operating with said leak port and adapted to be operated by said second pressureactuated means to completely open and comin a single short movement.

2. In combination, a casing and a pair of valves in said casing, one of said valves controlling a connection to a thermostat and the other valve controlling a connection to a heat control valve, said two valves being oppositely positioned, a diaphragm in said casing acting on said valves whereby movement of said diaphragm simultaneously closes one of said valves and opens the other, means providing a passage for fluid under pressureto the space behind said diaphragm, a leak port in said passage, a second diaphragm in said casing and a passage for fluid under pressure to the rear of said second diaphragm, said passage being open to fluid under pressure from asecond thermostat, a snap spring overlying said a leak port, and means connecting said second diaphragm to said snap spring whereby a relatively very slight movement of said second diaphragm pressure to the space behind said diaphragm, a

restriction in said passage, a leak port also in said passage between said diaphragm and'said restriction, a second diaphragm in said casing and a passage for fluid under pressure to the rear of said-second diaphragm, said passage being open to fluid under pressure from a second thermostat, a snap spring overlying said leak port, and means connecting said second diaphragm to said snap spring whereby a relatively very slight movement of said second diaphragm will cause said snap spring to cover or uncover said leak port.

4. In combination, a casing and a pair of valves in said casing, one of said valves controlling a connection to a thermostat and the other valve controlling a connection to a heat control valve, said two valves being oppositely positioned, a diaphragm in said casing acting onsaid valves whereby movement ofsaid diaphragm simultaneously closes one of said valves and opens the other, means providing a passage for fluid under pressure to the space behind said diaphragm, a

, leak port in said passage, a second diaphragm in said casing and a passage for fluid under pressure to the rear of said second diaphragm, said passage being open to fluid under pressure from a second thermostat, a snap spring overlying said leak port, and adjustable spring resisted means connecting said second diaphragm to said snap spring whereby a relatively very slight .movement of said second diaphragm will cause said snap spring to cover or uncover said port.

5. in combination, a casing and a pair of valves in said casing, one of said valves controlling a connection to a thermostat and the other valve controlling a connection to a heat control valve, said two valves being oppositely positioned, a diaphragm in said casing acting on said valves whereby movement of said diaphragm simultaneleakously closes one of said valves and opens the other, means providing a passage for fluid under pressure to the space behind said diaphragm, a restriction in said passage, a leak port also in said passage between said diaphragm and said restriction, a second diaphragm in said casing and a passage for fluid under pressure to the rear of said second diaphragm, said passage being open to fluid under pressure from a second thermostat, a snap spring overlying said leak port,

and means connecting said second diaphragm to said snap spring whereby a relatively very slight movement of said second diaphragm will cause said snap spring to cover or uncover said leak port, and an outletjrom said first-mentioned Y passage. also between said diaphragm and said restriction, said outlet providing for an air supply of the same pressure as that which is eflec- Live on said first diaphragm.

HARRY BARNETT. 

